When conveying loose material such as e.g. granulate, animal feed, cereals and similar it is very common to use so-called cup conveyors. The cups, which are typically made of a suitable type of plastic, are moved in an endless path between a filling station and an emptying station, and are distinguished by being pivotably suspended about a horizontal axis so that they always have the opening facing upwards. Filling of such cups are typically effected by letting the cups pass under a filling station with a chute and a dosing device. The dosed material slides down the chute in a continuous flow and down into the cup. The amount of dosed material is typically controlled by a damper or other suitable regulating mechanism in the dosing device. The degree of filling of individual cups is controlled by how much material is dosed per time unit compared with how fast the cups pass the filling station. In order to achieve optimal utilisation of such a cup conveyor it is desirable that the cups are filled sufficiently during the passage of the filling station. The speed at which the cups pass the filling station and the amount of the dosed material per time unit can be adjusted so that optimal filling of the cups is achieved while at the same time the desired amount of material is moved.
This form of filling, however, implies a problem as the material tends to accumulate at the trailing edge of the cup as seen in the direction of movement. This accumulation causes the cup to be unbalanced and possibly overturn at the subsequent vertical transport. Another problem is that the filling degree of the cups is reduced hereby. By low filling degree the system has to run more (i.e. for a longer time) or faster than if the filling degree is high, causing more wear and thus more maintenance on the system as such.
As the material is supplied to the cups in a continuous stream and in order to avoid spilling between the cups during filling, it is normal that the cups have an overlap at both ends. The overlapping parts of adjacent cups lie above and below each other, respectively. This overlapping, however, introduces some problems. Typically, some of the material will settle upon this overlap and have a tendency of being squeezed between the overlapping parts of two cups, causing damage to the cups or crushing of the material which becomes unwanted dust. Furthermore, these overlapping parts give rise to problems when the cups are to change direction of movement, e.g. from horizontal to vertical. In such a situation it is required that the overlapping parts of respective cups are disposed correctly in relation to each other such that the cup will not overturn when changing conveying direction from horizontal to vertical, or vice versa. In the worst case a wrong disposition will result in breaking of a cup and that the facility has to be stopped for replacing the broken cup. In order to avoid or at least limit these problems, such facilities are equipped with shifters which can determine which of the overlapping ends of the cups are to be at the top. If this overlap by the cups can be dispensed with, the mentioned shifters can be obviated in the system, and there will be a marked reduction in wear on the cups as they no longer need to be in direct mutual contact. By obviating overlapping between the cups and thereby also the shifters, such a system would be cheaper as well as more reliable.
Examples of rotary dispensers, e.g. for use with cup conveyors are disclosed in JP 61-263528 A, JP H03-038465 A, DE 3332861 A1 and GB 663493 A.
From DE 218608 is known a system wherein the cups are arranged without overlapping and where the material is supplied to a rotating lock wherein the material is fed to a compartment at the periphery of this lock and which is subsequently rotated and gradually emptied according to the rotation. The material is first measured—supplied to the compartment in the lock—and subsequently emptied into the cup. As the lock is rotated, the material is “dumped” and falls down into the cup in an uncontrolled stream. By this emptying which starts well above the upwardly facing opening of the cup and which is only finished after rotating at least 90°, there is a great risk that material from an overfilled compartment falls beside the cup. Moreover, this can be both dusty and damaging, rough treatment of the material. This is due to the design as the material is not conducted via any kind of chutes or the like for the cup and actually released from the lock at a rather great height above the cup, a reason why the apparatus according to DE 218608 leaves something to be desired.
Furthermore, there is the fact that if increased capacity is wanted it is not possible immediately to increase the rotary speed of the lock and the conveying speed of the cups as this will entail that the material in the lock is almost thrown out of the latter. Hereby an even greater spillage or loss of material will arise.
A further drawback of the solution as indicated in DE 218608 is that the material dosed and supplied to the cups via the lock very easily may get pinched between the rotating lock and the area at which the material is accumulated in front of the lock. Some of the material is hereby unavoidably crushed hereby, causing waste, and in some cases crushed material is entirely unwanted, being decisive as to whether the material can be used or not. At the same time this fact also entails an unacceptably extensive wear on the machine parts in contact with the material when the latter is crushed. It is therefore a great disadvantage that the apparatus is arranged such that material is accumulated in front of the rotating lock.
In principle, DE 218608 indicates a solution wherein the material is measured in a compartment and supplied to a cup. Thus there is no possibility of increasing the capacity beyond a given amount per time unit which is determined by the size of the compartment and the rotary speed of the lock which is subject to certain limitations as described above.